1. Technical Field
The disclosed embodiments relate to a multi-tuner system, and a receiver and a TV using the same. The disclosed embodiments have numerous applications, including but not limited to single package dual tuning systems for use in digital TVs with Digital Video Broadcast Terrestrial (DVB-T) receivers.
2. Related Art
Recently, signal processing has been required to be digitalized in a digital TV set or a set-top box for a digital TV according to the European Digital Video Broadcast Terrestrial (DVB-T) standards. It is desired to mount two or three tuners in each TV set or set-top box in order to use one of the tuners for TV receiving and the other for recording.
FIG. 1 is a conceptual view illustrating a conventional dual tuning system for a digital TV.
The conventional tuning system for a digital TV includes a first single conversion tuner 10 for converting a first Radio Frequency (RF) signal corresponding to a first selected channel into a first Intermediate Frequency (IF) signal, and a second single conversion tuner 20 for converting a second RF signal corresponding to a second selected channel into a second IF signal.
However, the conventional dual tuning system of FIG. 1, cannot function properly if IF interference on the same frequency or adjacent frequencies occurs between two tuners (e.g., a main tuner 10 and a sub-tuner 20) which use the same conversion mode. This causes a drawback in that the two tuners 10 and 20 cannot be installed in a single package. As can be seen in FIG. 1, the tuners of the conventional dual tuning system must be fabricated as two separate modules.
For example, in a DVB-T receiver having 36 MHz IF, when the first and second single conversion tuners 10 and 20 are tuned to select the same channel, e.g., 800 MHz RF, the oscillation frequencies of both the first and second conversion tuners 10 and 20 are 836 MHz. That is, the first and second single conversion tuners 10 and 20 have the same IF, which causes IF interference to occur.
Further, when the first and second single conversion tuners 10 and 20 are tuned to select adjacent channels, e.g., when the first single conversion tuner 10 selects 800 MHz RF with its oscillation frequency being tuned to 836 MHz, and the second conversion tuner 20 selects 808 MHz RF with its oscillation frequency being tuned to 844 MHz, the IF of the first single conversion tuner 10 (i.e., 836 MHz) is in such close proximity to the IF of the second single conversion tuner 20 (i.e.; 844 MHz) that IF interference is caused to occur.
In order to avoid such IF interference, the first and second single conversion tuners 10 and 20 can not be embodied in one package, and must be installed in their own packages separate from each other. Thus, two separate tuner packages need to be installed in each TV-set or receiver, resulting in a bulky structure.
There is a need for a multi-tuner system that can avoid or at least mitigate the above drawback of the conventional device.